3,3',4,4'-TETRACHLOROBIPHENYL EFFECTS ON ANTIOXIDANT ENZYMES AND GLUTATHIONE STATUS IN DIFFERENT TISSUES OF RAINBOW-TROUT

Polychlorinated biphenyls are known to cause induction in cytochrome P 45O-dependent monooxygenase activities and alteration in the antioxida nt defense of mammals. To determine whether similar detoxication proce sses are activated in rainbow trout (Oncorhynchus mykiss), we investig ated P450-dependent enzyme activities, antioxidant enzymes and glutath ione status (reduced and oxidized glutathione, GSH and GSSG) in this s pecies injected intraperitoneally with 3,3',4,4'-tetrachlorobiphenyl a t 5 mg/kg body weight 6 weeks post injection. Ethoxyresorufin O-deethy lase activities increased 11- and 40-fold in liver and kidney, UDPgluc ulonosyltransferase activities were 2- and 5-fold higher in these orga ns, while glutathione S-transferase activity was enhanced greater than 2-fold in liver of tetrachlorobiphenyl injected trout in comparison w ith controls. Glutathione peroxidase activities were increased in live r and white muscle of dosed fish. Tetrachlorobiphenyl exposure resulte d in a significant increase in glutathione reductase activities, with 7-fold enhancement in liver and significantly elevated activities in k idney, red and white muscles. Similarly, cytosolic superoxide dismutas e and catalase activities were increased in white muscle of injected t rout. Tetrachlorobiphenyl exposure significantly increased GSH concent rations in liver and kidney, while GSSG levels were increased in liver and blood plasma. These changes, however, did not modify the GSSG/GSH ratios in these tissues. Overall, these results imply a major tetrach lorobiphenyl effect on GSH status and antioxidant enzymes in trout tis sues and identify white muscle along with liver and kidney as importan t tissues in the detoxication process in this animal.